1. Field of the Invention
This invention relates to nickel (II) thiobis(alkylphenolates) complexed with thiobis(alkylphenols) as novel compounds and to organic compositions, normally subject to oxidative degradation such as lubricants and plastics, containing a minor amount of said nickel (II) phenolate complex sufficient to impart antioxidant, UV stabilization and energy quenching characteristics thereto.
A more particular aspect of this invention is directed to the above referred to novel complex and lubricant compositions containing same, which lubricant compositions include oils of lubricating viscosity, hydrocracked lubricating oils, hydraulic oils, mineral oils or fractions thereof, automotive oils, gear oils, transmission fluids, waxes, greases and other forms, natural or synthetic, of lubricants and distillate fuel oils. These fluids normally require the presence of stabilizing agents to inhibit oxidative degradation which may be catalyzed inter alia by ultraviolet light, the presence of metals or may occur as the result of high temperature conditions.
2. Description of the Prior Art
The production of lubricant compositions, for example, lubricating oils produced by hydrocracking provides a relatively high viscosity index oil and permits the use of base stocks that would be unsuitable for other purposes. On the other hand, however, hydrocracked lubricating oils tend toward poor stability against ultraviolet light degradation, rapidly forming suspended and/or precipitated insoluble material on exposure to ultraviolet light, such as sunlight, or other sources of actinic radiation. Compounds capable of absorbing ultraviolet light, for example, hydroxybenzophenones, and hydroxyphenyl benzotriazoles, have afforded some improvement in the light stability of hydrocracked oils. Additionally lubricants may be subjected to high temperatures which tend as mentioned heretofore to catalyze oxidative degradation.
Commercially available ultraviolet stabilizers are listed by class and function and identified as to structure in the Kirk-Othmer Encyclopedia in "Encyclopedia of Chemical Technology", Second Edition, Vol. 21, pp. 115-122. British patent specification No. 1,263,910 (1972) discloses bis(stilbene-dithiolato) nickel as an antioxidant for plastic materials. The British specification also cites superior hydroperoxide decomposition capability of this additive. U.S. Pat. No. 3,832,304 discloses the use of aromatic azo compounds for stabilizing hydrocracked oils. Additionally in the patent literature, for example, U.S. Pat. Nos. 3,149,007; 3,448,662; 3,450,636 and 3,654,329 disclose the use of nickel salts complexed with dithiophosphorous compounds as being useful in lube oils and functional fluids. Further, U.S. Pat. Nos. 2,703,786; 2,716,090 and 3,210,277 disclose the use of polyvalent metals, e.g., Ni salts of alkyl phenol sulfides as oxidation inhibitors and plasticizing agents.
None of the foregoing disclosures, however, are directed to organic compositions containing the organo-sulfur-nickel (II) complexes described in accordance with this invention. For example, U.S. Pat. No. 2,971,940 describes nickel 2,2'-thiobis-(4-t-octylphenolate), structure I ##STR1## and nickel 2,2'-thiobis-(4-t-octylphenol-phenolate), structure II ##STR2## The subject compounds possess different properties and structures from those of I and II identified above. Although they can be prepared by methods which may involve use of the same reactants used for the preparation of I or II, the method used herein apparently distinguishes the subject complexes, exemplified by their properties, from such prior art or other previously known compounds.